Author(s): Keränen Jukka, Hongisto Valtteri
Immission measurement of wind turbine noise is usually conducted using short-term measurements during a period of strong wind speed and full power output. However, the reliability of such noise immission results has been questioned by some researchers, residents and authorities. The aim of this study was to investigate long-term variation of sound pressure levels in a yard near a wind power area. The distance to the nearest wind turbine was 650 meters. The study period was over 5 months. The long-term measurement result attempted to determine the mean sound level, LA,eq, during the periods of maximum power output. The long-term measurement results did not involve the background noise correction so that the result was an overestimate of the true value. Despite of that, the long-term measurement result was in agreement both with the predicted LA,eq and with the measured LA,eq obtained by a short-term measurement in the same yard by an independent consulting company. The findings give no reason to doubt the validity of short-term measurements in this yard. However, further long-term measurements may be needed to validate our findings.
Name: Dr Jukka Keränen